10-06-2016, 12:08 PM
One of the first out of the job lot testkit box, and the easiest so far. Wooden ply case, toggle power switch with LED, BNC output, and a nine position rotary switch marked in KHZ steps (10, 12.5, 25, 50, 100, 125, 250, 500 and 1000). Inside, vero construction, 1000khz crystal with trimmer feeding into three CMOS chips, 2 x 4018 and 1 x 4069. Taps taken off at various points to the selector switch for the frequency settings. Smoothing capacitor for age when tested was quite good and clean, no degradation. All resistors being metal film were bang on. Build date indicates 1974 and the labels on at least one of the 4018s indicates a first generation chip.
Fresh 9v battery and power up. DSO plugged in as it's frequency counter is just about the most accurate I've got. Waveform at 1000khz not 100% great with some curve off but then what did I expect as it's raw and coming straight off the crystal generation circuit. Frequency at 1000khz is bang on, no adjustment needed, I'd make it worse, not better, reporting in at 1.00002. Frequency check taken at 100khz ( reporting 100.001 and 10.0000 repectively) with a nice sharp square wave signal.
Some case cleaning up, a polish, and 15 mins with pagemaker to knock up a new dial legend and this is one nice bit of kit.
Fresh 9v battery and power up. DSO plugged in as it's frequency counter is just about the most accurate I've got. Waveform at 1000khz not 100% great with some curve off but then what did I expect as it's raw and coming straight off the crystal generation circuit. Frequency at 1000khz is bang on, no adjustment needed, I'd make it worse, not better, reporting in at 1.00002. Frequency check taken at 100khz ( reporting 100.001 and 10.0000 repectively) with a nice sharp square wave signal.
Some case cleaning up, a polish, and 15 mins with pagemaker to knock up a new dial legend and this is one nice bit of kit.